1. **Problem Statement:**
Find the area between $z=0$ and given $z$-scores using the z-table (standard normal distribution).
2. **Using the z-table:**
The z-table gives the area from the mean (z=0) to a positive z-value. For negative z-values, use symmetry: area from 0 to $-z$ equals area from 0 to $z$.
3. **Part I: Areas between $z=0$ and given z-values**
A. $z=-1$
- Area from 0 to $-1$ equals area from 0 to 1.
- From z-table, area(0 to 1) = 0.3413.
B. $z=2.56$
- From z-table, area(0 to 2.56) = 0.4948.
C. $z=-1.28$
- Area from 0 to $-1.28$ equals area from 0 to 1.28.
- From z-table, area(0 to 1.28) = 0.3997.
4. **Part II: Convert raw scores to z-scores and find area between them**
Formula for z-score:
$$z = \frac{X - \mu}{\sigma}$$
where $X$ is the raw score, $\mu=48$ is the mean, and $\sigma=6$ is the standard deviation.
A. Scores 54 and 42
- $z_{54} = \frac{54-48}{6} = 1$
- $z_{42} = \frac{42-48}{6} = -1$
- Area between $z=-1$ and $z=1$ is twice area from 0 to 1:
$$2 \times 0.3413 = 0.6826$$
B. Scores 52 and 60
- $z_{52} = \frac{52-48}{6} = \frac{4}{6} = 0.67$
- $z_{60} = \frac{60-48}{6} = 2$
- Area from 0 to 0.67 = 0.2514 (from z-table)
- Area from 0 to 2 = 0.4772
- Area between 0.67 and 2 = $0.4772 - 0.2514 = 0.2258$
- Since 52 < 60 and both positive z, total area between 0.67 and 2 is 0.2258
C. Scores 55 and 60
- $z_{55} = \frac{55-48}{6} = 1.17$
- $z_{60} = 2$ (from above)
- Area(0 to 1.17) = 0.3790
- Area(0 to 2) = 0.4772
- Area between 1.17 and 2 = $0.4772 - 0.3790 = 0.0982$
D. Scores 48 and 42
- $z_{48} = 0$
- $z_{42} = -1$
- Area between 0 and -1 equals area(0 to 1) = 0.3413
E. Scores 54 and 38
- $z_{54} = 1$
- $z_{38} = \frac{38-48}{6} = -1.67$
- Area(0 to 1) = 0.3413
- Area(0 to 1.67) = 0.4525
- Total area between -1.67 and 1 is sum of areas from 0 to 1 and 0 to 1.67:
$$0.3413 + 0.4525 = 0.7938$$
**Final answers:**
I.
A. 0.3413
B. 0.4948
C. 0.3997
II.
A. 0.6826
B. 0.2258
C. 0.0982
D. 0.3413
E. 0.7938
These areas represent probabilities or proportions of the standard normal distribution between the given z-values or raw scores.
Z Table Areas 90F953
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